Digital cameras are used in a variety of consumer, industrial and scientific imaging devices to produce still images and/or video. Such digital cameras are for example implemented in webcams and mobile telephones and include a camera module such as a reflowable camera module (RCM) attached to a printed circuit board (PCB). The field of view (FOV) of an RCM is typically between 60 degrees and 70 degrees. The FOV can be increased by attaching an adapter lens in front of the camera module. The resulting imaging system (adapter lens plus camera module) has a wider FOV than the camera module alone. A wide FOV is valuable in applications such as autonomous vehicle navigation, car parking monitor systems, and gesture recognition.
An adapter lens that provides an ultra-wide field of view, e.g., 180°, is called a fisheye adapter lens or fisheye conversion lens. Existing fisheye adapter lenses removably attach to the outside of a digital camera. In one example a clip is used to attach the fisheye adapter lens to the digital camera so that it aligns with the camera module. In another example, a case encloses a mobile device (e.g., a cell phone) that includes an internal camera module and holds the fisheye adapter lens adjacent to the internal camera module.